The long term goal of this project is the development of a reliable, low-cost control system for externally powered upper-extremity orthotic devices that will provide high level quadriplegics with volitional control of an arm and therefore enable them to be less dependent on outside assistance in the performance of many everyday activities. In order to make this voluntary motion appear natural, a control system will be developed which permits a patient to specify desired motion in a spatial coordinate system and have the controller determine the necessary simultaneous rate of change in joint angles to achieve the desired motion. The system necessary to accomplish this will consist of control signal transducers, which will be used by the patient to specify direction and rate of motion of the hand; an electronic coordinate converter to translate the input control signals into signals specifying the desired rate of motion of the individual joint angles; and an electronic motor controller to power the motors of the electric arm. For those who do not need complete external powering a partially powered elevating ball-bearing feeder will be used. A major effort of this research will be an investigation of control strategies to give the patient maximum volitional function with simple commands and the implementation of these strategies in a self- contained, battery powered, unit which will fit on the back of an electrically powered wheelchair. The total system will be completely controllable by the patient without external assistance needed except for application and removal. The tolerance of the patient for sitting will be the limiting factor on duration of daily use.